1. Field of the Invention
The invention relates to the field of stabilized vehicles and, particularly, to truck and tractor vehicles which are employed for hauling loads upon the public highways.
2. Description Of The Prior Art
Because the suspension systems of trucks, and of tractors which are intended to be coupled to, and pull semi-trailers necessarily must be of such a nature as to sustain heavy loads, when such trucks and tractors are operated without load they have always been found to jar and vibrate, particularly when driven over roads which are not perfectly smooth, to such an extent that they not only produce considerable discomfort and annoyance to the operator, but they can, if driven empty over prolonged periods of time with such jarring and vibration, begin self-destruction in the weaker areas of the truck or tractor structure.
Although many efforts have been made by truck builders to reduce such jarring and vibration when their trucks are operated without load, heretofore none of such efforts appears to have met with any degree of success. Among such efforts, as may be seen in U.S. Pat. Nos. 2,929,619 and 2,947,531, has been the incorporation of pneumatic devices, such as bellows air type springs interposed adjacent each wheel between the axle and the frame and regulated by automatic valve means of the types disclosed in these patents. Notwithstanding the fact that the expedients disclosed in these two patents were devised almost twenty years ago, they do not appear to have been widely adopted, if at all, in any trucks or tractors offered today.
Other efforts to solve the jarring and vibration problem by providing pneumatic springs and control devices are exemplified by the following further patents, namely, U.S. Pat. Nos. 2,943,851, 3,215,339, 2,624,594, 2,879,077 and 2,989,301. Also, as may be seen in U.S. Pat. Nos. 3,137,515, 3,203,711 and 3,227,470, expandable bellows have been utilized in other ways in connection with trucks and trailers. However, in none of these prior art patents has any thought ever been given to utilizing pneumatic bellows for the purpose of stabilizing a truck or tractor during its operation without load except in the form of the unsuccessful efforts referred to above where pneumatic springs have been attempted to be substituted for the various spring-type suspension systems.
Thus, despite all of these prior art efforts to employ pneumatic devices, including expandable bellows, no one, prior to the present invention, has succeeded in devising any way for stabilizing trucks and tractors to eliminate or minimize jarring and vibration during empty operation.